DE102022108996A1 - LIGHT CONDUCTING ELEMENT, FOR EXAMPLE, FOR EXHAUST SIGN LIGHTS - Google Patents

Abstract

A light guide element (10), for example for an escape sign light (100), has a plate-shaped light guide (11) with an elongated light coupling side (15) formed on a narrow side of the light guide (11), which is designed for the coupling of light from an elongated light source, wherein the light guide (11) is designed to radiate light irradiated via the light input side (15) flatly on at least one flat side (12) which is essentially perpendicular to the light input side (15), and means for coupling out the light via the flat side (12) of the light guide (11). wherein the means for coupling out the light are formed by a coating (20) of the corresponding flat side (12) of the light guide (11), the coating (20) being porous at least in the area adjacent to the light guide (11).

Description

The present invention relates to a plate-shaped light-guiding element, which is intended, for example, for use in an escape sign light.

Different types of escape sign lights are known from the prior art. Modern and aesthetically appealing escape sign lights usually have an external light-guiding element, with at least one escape sign with an escape route direction indicated on it usually being attached to the flat sides of the light-guiding element. With such escape sign lights, light is usually coupled into it from a narrow side of the light-guiding element, with the light being emitted mainly via the flat sides after appropriate forwarding, so that the escape sign, together with the escape route direction shown, is easily and clearly recognizable. Such escape sign lights with a light guide are, for example, from EP 2 648 178 B1 known.

The escape sign is usually displayed using a colored so-called pictogram, which should appear uniformly bright using the light-guiding element. The homogeneous, uniform light emission required for this over a larger area is usually achieved with light-guiding elements by specifically providing decoupling measures on the flat side intended for light emission, with the help of which the light transmitted by means of total reflections within the light-guiding element is decoupled. These can be roughenings or comparable structures that couple out part of the light from the side of the light-guiding element, but transmit another part by means of total reflection, so that uniform light emission across the entire surface is possible.

As already mentioned, pictograms of escape sign lights are colored representations that are intended to be evenly illuminated by the light transmitted in the light guide, which is usually color-neutral. The question then arises as to how the information representing the pictogram is attached to the outside of the light-guiding element.

The obvious measure is to provide the surface of the light-guiding element used to represent the escape route with a layer of color or a colored representation. This could be done, for example, by printing on the light guide or in another way, which would represent a simple measure in terms of manufacturing technology.

However, paint applied directly to the surface of a light-guiding element leads to the direct coupling out of the light striking the paint layer, since the corresponding pigments of the paint scatter the light in such a way that it is no longer transmitted by means of total reflection. This procedure therefore only makes sense if it is otherwise ensured that light coupled into the light guide can also reach areas remote from the light coupling side. Accordingly, this solution is only practical for relatively thick light guides or light guides which are designed to taper in a wedge shape starting from the light input side. However, in the case of rather thin light guides, which are only a few millimeters thick, this procedure would lead to a non-homogeneous light emission, since only a very small proportion of light would be passed on to more distant areas of the light guide.

Accordingly, solutions were sought to achieve uniform light emission even with relatively thin light-guiding elements. Such solutions are predominantly based on the fact that the pictogram is implemented using a separate component that is not responsible for the actual light extraction from the light-guiding element. For example, the pictogram can be in the form of a film or another thin disk, which then rests on the outer surface of the light-guiding element. This can then be designed in such a way that a homogeneous and uniform light emission takes place over the entire surface using suitable light decoupling structures. However, such measures obviously lead to increased effort because an additional component is required.

The present invention is therefore based on the task of offering a novel possibility of being able to achieve uniform light extraction even with very thin light-guiding elements, but of reducing the effort required to illuminate, for example, a pictogram or other graphic information.

The object is achieved by a light-guiding element which has the features of claim 1 and by a method according to claim 14. Advantageous developments of the invention are the subject of the dependent claims.

The concept according to the invention provides, analogously to thick or wedge-shaped light-guiding elements th to provide the flat side of the light guide directly with a coating which, for example, contains the information regarding the escape route display to be displayed. According to the invention, however, it is now provided that this coating is designed to be porous at least in the area adjacent to the light guide.

This measure means that, in contrast to previously known solutions, light striking the coating is not completely coupled out, but only a part of it. Another part, which hits a corresponding pore, i.e. an air pocket within the coating, in the border area between the light guide and the coating, is totally reflected and can therefore continue to migrate within the light-guiding element. This ensures that light is ultimately emitted over the entire flat side of the light-guiding element. The coating therefore serves, on the one hand, to display the desired information, and on the other hand, it represents a suitable measure for light extraction, which, however, is now designed analogously to classic light extraction structures in such a way that a homogeneous and uniform light emission can be achieved.

• • einen plattenförmigen Lichtleiter mit einer an einer Schmalseite des Lichtleiters ausgebildeten, länglichen Lichteinkoppelseite, welche für die Einkopplung von Licht einer länglichen Lichtquelle ausgebildet ist, wobei der Lichtleiter dazu ausgebildet ist, über die Lichteinkoppelseite eingestrahltes Licht an zumindest einer im Wesentlichen senkrecht zur Lichteinkoppelseite ausgerichteten Flachseite flächig abzustrahlen, sowie
• • Mittel zur Auskopplung des Lichts über die Flachseite des Lichtleiters,

wobei erfindungsgemäß die Mittel zur Auskopplung des Lichts durch eine Beschichtung der entsprechenden Flachseite des Lichtleiters gebildet sind und wobei die Beschichtung zumindest in dem an den Lichtleiter angrenzenden Bereich porös ausgebildet ist.According to the present invention, a light-guiding element is proposed, for example for an escape sign light, the light-guiding element having:

• • a plate-shaped light guide with an elongated light coupling side formed on a narrow side of the light guide, which is designed for the coupling of light from an elongated light source, the light guide being designed to transmit light irradiated via the light coupling side to at least one flat side aligned essentially perpendicular to the light coupling side radiate flatly, as well as
• • Means for coupling out the light via the flat side of the light guide,

wherein, according to the invention, the means for coupling out the light are formed by a coating on the corresponding flat side of the light guide and the coating is designed to be porous at least in the area adjacent to the light guide.

The measure according to the invention therefore represents a particularly elegant way of backlighting graphic information over a large area using a light guide. As already explained, the coating in the present case fulfills two functions: on the one hand, it serves to display the graphic information, and on the other hand, it is responsible for the desired uniform coupling of the light from the light guide.

The coating can in particular be at least partially colored, although it is of course conceivable that areas with different colors are provided. Even a coating in just a single color would be conceivable in principle, in which case the coating would primarily serve to uniformly decouple the light from the light guide. In this case, the light-guiding element according to the invention would not be used to display information but primarily as a larger luminous surface for lighting purposes.

According to the present invention, the light guide preferably has a thickness of approximately two to four millimeters, in particular a thickness of approximately 3 millimeters. The coating can cover the corresponding side of the light guide, in particular over a large area. In principle, however, it would also be conceivable to apply the coating only in the form of certain structures or patterns, depending on the type of light extraction desired.

Analogous to known light coupling structures for light guides, it can also be provided that a density of pores contained in the coating decreases with increasing distance from the light coupling side. This measure takes into account that the proportion of light within the light guide decreases as the distance from the light input side increases, since part of the light has already been coupled out. By reducing the pore density and thus increasing the efficiency of light extraction, this is taken into account and ensures that, despite everything, there is a homogeneous light output overall.

The coating can also be designed in such a way that, viewed overall, it has a light-concentrating effect. This can then be realized, for example, by having the outside of the coating facing away from the light guide shaped or structured accordingly. Alternatively, it would also be conceivable to design the coating in such a way that it has a light-scattering effect. This is particularly useful if, for example with escape sign lights, the corresponding backlit symbol needs to be clearly visible from all directions.

Of course, it would be conceivable for not just one, but both flat sides of the light-guiding element to have a corresponding coating.

The application of the coating according to the invention in such a way that corresponding pores are formed at least in the border region can be carried out in different ways. The use of a 3D printing process is particularly preferred, which opens up the possibility of specifically influencing the design and density of the pores in the border area. This leads to a particularly simple and cost-effective production of the light-guiding element.

According to the invention, a lamp is also proposed which has elongated lamps and a light-guiding element assigned to the lamps, which is designed as described above. In particular, this light can be an escape sign light.

1. a) Bereitstellen eines plattenförmigen Lichtleiters mit einer an einer Schmalseite des Lichtleiters ausgebildeten, länglichen Lichteinkoppelseite, welche für die Einkopplung von Licht einer länglichen Lichtquelle ausgebildet ist, wobei der Lichtleiter dazu ausgebildet ist, über die Lichteinkoppelseite eingestrahltes Licht an zumindest einer im Wesentlichen senkrecht zur Lichteinkoppelseite ausgerichteten Flachseite flächig abzustrahlen, und
2. b) Beschichten der zur Lichtabgabe vorgesehenen Flachseite des Lichtleiters derart, dass in dem an den Lichtleiter angrenzenden Bereich die Beschichtung porös ausgebildet ist.

Furthermore, according to the invention, a method for producing a light-guiding element is proposed, the method comprising:

1. a) Providing a plate-shaped light guide with an elongated light coupling side formed on a narrow side of the light guide, which is designed for the coupling of light from an elongated light source, the light guide being designed to transmit light irradiated via the light coupling side to at least one substantially perpendicular to the light coupling side to be radiated flat on the aligned flat side, and
2. b) Coating the flat side of the light guide intended for light emission in such a way that the coating is porous in the area adjacent to the light guide.

• 1 ein Anwendungsbeispiel eines erfindungsgemäßen Lichtleitelements in Form einer Rettungszeichenleuchte;
• 2 eine schematische Schnittdarstellung eines erfindungsgemäßen Lichtleitelements; und
• 3 eine vergrößerte Darstellung der erfindungsgemäß ausgestalteten Beschichtung.

The invention will be explained in more detail below with reference to the accompanying drawing. Show it:

• 1 an example of an application of a light-guiding element according to the invention in the form of an escape sign light;
• 2 a schematic sectional view of a light-guiding element according to the invention; and
• 3 an enlarged view of the coating designed according to the invention.

As an application example for the present invention is in 1 a typical escape sign light is shown, which is provided with the reference number 100. It should be noted, however, that the solution according to the invention can not only be used for light-guiding elements for such escape sign lights, but is generally practical for flat light-guiding elements that are intended in particular for the graphic representation of luminous information. For example, the concept according to the invention would also be suitable for advertising boards, signs or comparable applications.

The escape sign lamp 100 therefore initially has an elongated, approximately cuboid-shaped housing 110, in which lamps (not shown) and electronic components 115 for operating the lamps are arranged. A flat light-guiding element 10 extends vertically from the underside of the housing 110, which is ideally very thin and has a thickness d of only a few millimeters. With the usual dimensions of the escape route symbol shown, it is provided in particular that the thickness d is only in the range between 2 and 4 millimeters, in particular 3 millimeters.

The light-guiding element 10 primarily consists of a flat light guide 11, the top side 15 of which forms an elongated light coupling surface which is assigned to the lighting means, not shown. Light is irradiated into the plate-shaped light guide 11 via this light coupling surface 15 and passed on in a known manner by means of total reflections in such a way that it is distributed over the entire light guide 11.

On at least one flat side, here on the front 12 of the light guide 11, it is then provided that the light is emitted laterally, with the help of the emitted light being used to display the colored pictogram 50 on this flat side 12, with the help of which the direction of an escape route is displayed in the present application example is to be illuminated. In order to enable this uniform illumination of the pictogram 50, the light guide 11 must be designed in such a way that the light irradiated on only one side, namely the light input side 15, is emitted as evenly and homogeneously as possible over the corresponding flat side 12.

As already explained, it is now provided according to the invention that the outer surface of the light guide 11 itself does not have any corresponding light decoupling structures, but is instead provided with a suitable coating which fulfills this function. This inventive concept is based on the 2 and 3 can be seen, which show a sectional view of the light guide 11 with the coating 20 according to the invention arranged on an outside 12.

The special feature of the coating 20 applied according to the invention to the outer surface 12 of the light guide 11 is that it is not completely closed, as would usually be the case with colored coatings in the form of varnishes or the like. Instead, the coating is - like that 2 and 3 show - designed in such a way that it contains a large number of air pockets or pores 25. What is crucial for the effect according to the invention is that these pores 25 are at least partially in the border area to the surface 12 of the light guide 11. This means that at the points in which a corresponding pore 25 is present, a transition to air or the gas enclosed in the pore 25 takes place at the interface of the light guide 11 to the outside.

As is usual with light guides, this then has the consequence that light rays striking such pores 25 cannot leave the light guide 11, but are totally reflected here and thus passed on within the light guide 11. This can be seen, for example, in 3 light beam 11 shown, designated A, which impinges on the pore 25a. A ray of light (in 3 denoted by B), on the other hand, which does not encounter a pore 25 in the border area of the light guide 11, can leave the light guide 11 due to the material for the coating 20 and is decoupled accordingly. This light beam will then possibly pass through further pores 25 of the coating 20 in the further course. However, these only result in at most a slight deflection of this light beam and may therefore cause a certain amount of scattering of the coupled-out light. However, they do not prevent the light beam B from leaving the light guide 11 and the coating 20 applied thereto.

The decisive factor as to whether a light beam is coupled out of the light guide 11 is whether it hits a pore 25 of the coating in the transition region to the coating 20 or not. It is therefore essential for the effect according to the invention that the coating 20 forms the mentioned pores 25 at least at the border region to the light guide 11.

The particular advantage of the solution according to the invention is that, of course, the coating 20 can be designed in color and can therefore be used to display the pictogram. At the same time, however, it also fulfills the function of the light extraction elements of a classic light guide, so that additional measures for light extraction can be dispensed with.

A further advantage of the solution according to the invention is that the density of the pores 25 in the coating 20 can be influenced in a targeted manner. In particular, there is the possibility of designing the coating 20 in such a way that the density of the pores decreases as the distance from the light input side 15 of the light guide 11 increases. Analogous to classic light decoupling structures, this takes into account the fact that, due to the light decoupling, increasingly less light can reach areas of the light guide 11 that are further away from the light coupling side 15. By reducing the pores 25 or pore density, which has the same effect as an increase in classic light coupling structures, this circumstance is taken into account and ensures that despite everything, light remains over the entire surface of the light guide 11, in particular regardless of the distance to the light coupling side 15 is delivered. Homogeneous and uniform illumination of the pictogram 50 is guaranteed in this way.

The concept according to the invention can be implemented using all procedures for coating the light guide, which ensure that the above-described pores or other air inclusions are formed in the border area. For example, a coating using digital printing, screen printing or painting would be an option. In particular, coatings using 3D printing processes or laser sintering or selective laser sintering would be conceivable. Coating processes using wet phases, gas phases or emulsions or dispersions or combinations thereof would also be conceivable.

As already mentioned, a coating using 3D printing is particularly preferred, since it is possible here in a particularly simple manner not only to influence the color of the coating and thus the display of information, but also to influence the density of the pores essential to the invention. A light guide in the embodiment according to the invention can be produced very easily and cost-effectively in this way and is further characterized by the fact that it ultimately consists of only a single component, namely the directly coated light guide itself. Separate components such as correspondingly thin disks or foils, which contain the pictogram to be illuminated, can then be dispensed with.

Coating the light guide using 3D printing also has the advantage that the shape of the outer surface of the coating can also be specifically influenced, which opens up the possibility of influencing the light emission in the desired way. For example, it would be conceivable to provide the outside of the coating with a corresponding surface shape that has a light-concentrating effect and in particular directs the light in a desired direction. Of course, it would also be conceivable to provide the outer surface of the coating with structures that have a light-scattering effect, which would then emit light into as many areas as possible directions is promoted, resulting in better visibility of the glowing pictogram from different directions.

As already mentioned, the concept can also be used in general for targeted, homogeneous light extraction from light guides. This means that light guides that are used purely for lighting purposes or are only intended to represent luminous surfaces could also be coated in the manner according to the invention in order to be able to easily achieve uniform and homogeneous light emission. Since in this case the focus is primarily on light extraction and light emission, rather than the backlighting of symbols or the like, it would also be conceivable that the outer surface of the light guide is not provided with the coating according to the invention over its entire or at least large area. Instead, only certain areas could be specifically coated or the coating could be applied in the form of regular patterns or structures in order to achieve a special appearance in terms of light emission.

The possible applications for the concept according to the invention are accordingly very diverse.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2648178 B1 [0002]

Claims (13)

Light-guiding element (10), for example for an escape sign light (100), the light-guiding element (10) having: • a plate-shaped light guide (11) with an elongated light coupling side (15) formed on a narrow side of the light guide (11), which is for the coupling of Light from an elongated light source is formed, wherein the light guide (11) is designed to radiate light irradiated via the light coupling side (15) flat on at least one flat side (12) which is aligned essentially perpendicular to the light coupling side (15), • Means for coupling out the light via the flat side (12) of the light guide (11), characterized in that the means for coupling out the light are formed by a coating (20) of the corresponding flat side (12) of the light guide (11), the coating (20) being at least in the area adjacent to the light guide (11) is porous. Plate-shaped light-guiding element Claim 1 , characterized in that the coating (20) is at least partially colored, in particular has areas with different colors. Plate-shaped light-guiding element according to one of the preceding claims, characterized in that the light guide (11) has a thickness (d) of approximately 2-4mm, in particular is approximately 3mm thick. Plate-shaped light-guiding element according to one of the preceding claims, characterized in that the coating (20) covers the corresponding side (12) of the light guide (11) in an at least partially closed area. Plate-shaped light-guiding element according to one of the Claims 1 until 3 , characterized in that the coating (20) is applied in the form of patterns or regular structures to the outer surface (12) of the light guide (11). Plate-shaped light-guiding element according to one of the preceding claims, characterized in that a density of pores (25) contained in the coating (20) increases with increasing distance from the light coupling side (15). Plate-shaped light-guiding element according to one of the preceding claims, characterized in that the coating (20) has a light-concentrating effect. Plate-shaped light-guiding element according to one of the Claims 1 until 6 , characterized in that the coating (20) has a light-scattering effect. Plate-shaped light-guiding element according to one of the preceding claims, characterized in that both flat sides (12) of the light-guiding element have a coating (20). Plate-shaped light-guiding element according to one of the preceding claims, characterized in that the coating is applied by means of 3D printing. Luminaire (100), comprising elongated lamps and a light-guiding element (10) assigned to the lamps according to one of the preceding claims. Shine on Claim 11 , characterized in that it is an escape sign light. Method for producing a light-guiding element (10), the method comprising: a) Providing a plate-shaped light guide (11) with an elongated light coupling side (15) formed on a narrow side of the light guide (11), which is designed for the coupling of light from an elongated light source, the light guide (11) being designed for this purpose the light input side (15) is irradiated flatly on at least one flat side (12) aligned essentially perpendicular to the light input side (15), and b) coating the flat side (12) of the light guide (11) intended for light emission in such a way that the coating (20) is porous at least in the area adjacent to the light guide (11).

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